<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta http-equiv="x-ua-compatible" content="ie=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
  <title>Cropper.js</title>
  <link rel="stylesheet" href="../css/cropper.css">
  <style>
    .container {
      margin: 20px auto;
      max-width: 640px;
    }

    img {
      max-width: 100%;
    }

    .cropper-view-box,
    .cropper-face {
      background-color: black;
      opacity: 1;
    }

  </style>
</head>
<body>
  <div class="container">
    <h1>Mask an image (Redaction)</h1>
    <h3>Image</h3>
    <div>
      <img id="image" src="../images/picture.jpg" alt="Picture">
    </div>
    <h3>Result</h3>
    <p><button type="button" id="button">Mask</button></p>
    <div id="result"></div>
  </div>
  <script src="../js/cropper.js"></script>
  <script>
    function getMaskedCanvas(sourceCanvas, sourceImage, cropper) {
      var canvas = document.createElement('canvas');
      var context = canvas.getContext('2d');
      var maskWidth = cropper.getData().width;
      var maskHeight = cropper.getData().height;
      var maskTop =  cropper.getData().y;
      var maskLeft =  cropper.getData().x;
      var imageWidth = cropper.getImageData().naturalWidth;
      var imageHeight = cropper.getImageData().naturalHeight;
      var imageLeft = cropper.getImageData().left;
      var imageTop = cropper.getImageData().top;
      var imageAspect = cropper.getImageData().aspectRatio;

      canvas.width = imageWidth;
      canvas.height = imageHeight;

      // Debug
      console.log('Image Width: ' + imageWidth  + ' Image Height: ' + imageHeight + ' Image Aspect Ratio: ' + imageAspect );
      console.log('Image Left: ' + imageLeft  + ' Image Top: ' + imageTop );
      console.log('Mask Width: ' + maskWidth + ' Mask Height: ' + maskHeight + ' Mask Left: ' + maskLeft + ' Mask Top: ' + maskTop);

      context.imageSmoothingEnabled = true;
      context.drawImage(image, 0, 0, imageWidth, imageHeight);
      context.fillRect(maskLeft, maskTop, maskWidth, maskHeight);
      return canvas;
    }

    window.addEventListener('DOMContentLoaded', function () {
      var image = document.getElementById('image');
      var button = document.getElementById('button');
      var result = document.getElementById('result');
      var croppable = false;
      var cropper = new Cropper(image, {
        viewMode: 0,
        guides: true,
        center: true,
        highlight: true,
        cropBoxMovable: true,
        cropBoxResizable: true,
        ready: function () {
          croppable = true;
        },
      });

      button.onclick = function () {
        var croppedCanvas;
        var maskedCanvas;
        var maskedImage;

        if (!croppable) {
          return;
        }

        // Crop
        croppedCanvas = cropper.getCroppedCanvas();

        // Mask
        maskedCanvas = getMaskedCanvas(croppedCanvas, image, cropper);

        // Show
        maskedImage = document.createElement('img');
        maskedImage.src = maskedCanvas.toDataURL();
        result.innerHTML = '';
        result.appendChild(maskedImage);
      };
    });
  </script>
</body>
</html>
